This invention relates generally to gas turbine engines, and more particularly to methods and apparatus for assembling gas turbine engines.
In at least some known gas turbine engines, axisymmetric hardware, such as seals and/or hardware that delivers secondary airflow to an interior of the gas turbine engine, are supported adjacent to segmented flowpath components such as nozzles or transition ducts. During operation, thermal differentials between the axisymmetric hardware and the segmented flowpath components may result in destructive thermal stresses being induced between the axisymmetric hardware and the segmented flowpath components. Although providing for relative radial movement between the segmented flowpath components and the axisymmetric hardware may facilitate reducing such destructive thermal stresses, such arrangements make it more difficult to maintain at least some of the axisymmetric hardware substantially concentric to the engine centerline axis to facilitate proper operation of the air seals and a reduction in the rubs between the air seals and the segmented flowpath components.
For example, at least one known gas turbine engine includes a plurality of radial tabs that are formed integrally with a nozzle inner band to support the interior hardware such that a predetermined separation is facilitated to be maintained between the interior hardware and the segmented flowpath components. Moreover, a plurality of radial grooves engage the tabs and permit relative radial movement while maintaining the orientation of the interior hardware axially and circumferentially. However, when the nozzle tabs are engaged within the radial grooves during engine assembly, relative clearances defined between the nozzle tabs and the radial grooves may exceed predetermined tolerances resulting in a misalignment between the inner hardware and the segmented flowpath components.
Another known gas turbine engine includes a combustor casing that includes a plurality of radial pins having a first diameter, and a cowl boss that includes a plurality of holes having a second diameter that is at least fifty thousandths of an inch larger than the first diameter. The plurality of radial pins engage the plurality of radial holes to permit relative radial movement while positioning the cowl boss within the combustor casing. However, when the radial pins are engaged in the radial holes, the relative clearances defined between the radial pins and the radial holes may exceed predetermined tolerances resulting in a misalignment between the combustor casing and the cowl boss.